C5 Chemical Changes

Question 1

A salt

Answer 1

Compound formed during a neutralisation reaction when some or all hydrogen ions in an acid are replaced with metal ions or ammonium ions

Question 2

Neutralisation reaction

Answer 2

When an acid and a base are added together they cancel each other out and form a neutral solution

Question 3

How to make a salt by reacting a metal with an acid

Answer 3

Salt is formed by replacing hydrogen ions in the acid with metal ions or aluminum ions

Question 4

The reaction between a metal and an acid

Answer 4

Metal + acid ——> salt + hydrogen

Question 5

A salt formed between a metal and sulfuric acid or hydrochloric acid

Answer 5

Salt will be chloride if acid is hydrochloric acid

Salt will be sulphate if acid is sulphuric acid

Question 6

Which species is oxidised and which is reduced
in a reaction

Answer 6

The species that loses electrons is oxidized

The species that gains electrons is reduced

Question 7

The reaction between a metal oxide or metal hydroxide and an acid

Answer 7

Acid + metal oxide = corresponding salt + water

Question 8

Why the reaction between a base and a dilute acid is a neutralisation reaction

Answer 8

If a base is added to an acidic solution the solution becomes less acidic and moves toward the middle of the pH scale

Question 9

How alkalis are a subgroup of bases

Answer 9

An alkali is a water-soluble base

Bases which can be dissolved in water to furnish OH-ions

Question 10

How to make a salt reacting a metal carbonate with a dilute acid

Answer 10

Dilute hydrochloric acid

Add powdered zinc carbonate to acid

Continue to add powder until excess amount

Filter mixture in beaker to remove excess zinc

Question 11

What happens when ammonia react with acid

Answer 11

Formation of a salt of weak bases and strong acid

Question 12

Balanced equation for neutralisation reaction

Answer 12

NaOH + HCl ————> NaCl + H2O

Question 13

How to use universal indicator to classify as acidic or alkaline

Answer 13

Few drops of universal indicator solution is added to each substance at a time

The colour obtained is compared to pH chart to give pH of solution

Question 14

pH scale

Answer 14

Measures how acidic an object is

Lowest 0 highest 14

Pure water has pH 7

Question 15

Alkali effect on solution

Answer 15

A base or an alkali takes up hydrogen ions

Question 16

Example of alkali

Answer 16

Sodium hydroxide

Question 17

Example of a neutral

Answer 17

Pure water

Question 18

Example of a base

Answer 18

Copper oxide

Question 19

Acidic chemical example

Answer 19

Hydrochloric acid

Question 20

Relationship between alkalis and bases

Answer 20

Alkali is a base

A base that dissolves in water

Not all bases are alkali but all alkali is base

Question 21

How the pH of a solution changes as acid or alkali is added

Answer 21

pH below 7 is acidic

pH above 7 is alkaline

Acid added = pH decreases

Alkali added = pH increases

Question 22

Examples of strong acids

Answer 22

Hydrochloric acid (HCl)

Sulfuric acid (H2SO4)

Nitric acid (HNO3)

Question 23

Examples of weak acids

Answer 23

Acetic acid

Citric acid

Carbonic acid

Question 24

How an acid or alkali can be concentrated or dilute

Answer 24

By adding water to a concentrated acid or base, the solution is diluted

Question 25

How an acid or alkali can be strong

Answer 25

A strong acid is one that’s nearly or completely ionised in water

Question 26

How an acid or alkali can be weak

Answer 26

If it’s only partially ionised in water

Question 27

How concentration of hydrogen ions relates to pH number

Answer 27

As concentration of hydrogen ions increase the pH decreases

Question 28

Acid

Answer 28

A substance that produces hydrogen ions when dissolved in water